On Thu, Apr 06, 2023 at 07:43:27PM +0300, Daniel Matyas wrote: > MAX31827 is a low-power temperature switch with I2C interface. > > The device is a ±1°C accuracy from -40°C to +125°C > (12 bits) local temperature switch and sensor with I2C/SM- > Bus interface. The combination of small 6-bump wafer-lev- > el package (WLP) and high accuracy makes this temper- > ature sensor/switch ideal for a wide range of applications. > > Signed-off-by: Daniel Matyas <daniel.matyas@xxxxxxxxxx> > --- > MAINTAINERS | 1 + > drivers/hwmon/Kconfig | 11 ++ > drivers/hwmon/Makefile | 1 + > drivers/hwmon/max31827.c | 240 +++++++++++++++++++++++++++++++++++++++ Documentation/hwmon/max31727.rst missing. > 4 files changed, 253 insertions(+) > create mode 100644 drivers/hwmon/max31827.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index 549cea6bc340..63c17195a99b 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -12541,6 +12541,7 @@ L: linux-hwmon@xxxxxxxxxxxxxxx > S: Supported > W: http://ez.analog.com/community/linux-device-drivers > F: Documentation/devicetree/bindings/hwmon/adi,max31827.yaml > +F: drivers/hwmon/max31827.c > > MAX6650 HARDWARE MONITOR AND FAN CONTROLLER DRIVER > L: linux-hwmon@xxxxxxxxxxxxxxx > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig > index 5b3b76477b0e..80c44a787d42 100644 > --- a/drivers/hwmon/Kconfig > +++ b/drivers/hwmon/Kconfig > @@ -2401,4 +2401,15 @@ config SENSORS_ASUS_EC > > endif # ACPI > > +config MAX31827 > + tristate "MAX31827 low-power temperature switch" > + depends on I2C > + select REGMAP_I2C > + help > + If you say yes here you get support for MAX31827 > + low-power temperature switch and sensor connected with I2C. > + > + This driver can also be built as a module. If so, the module > + will be called max31827. > + > endif # HWMON > diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile > index 88712b5031c8..d00f0a1e73f6 100644 > --- a/drivers/hwmon/Makefile > +++ b/drivers/hwmon/Makefile > @@ -224,3 +224,4 @@ obj-$(CONFIG_PMBUS) += pmbus/ > > ccflags-$(CONFIG_HWMON_DEBUG_CHIP) := -DDEBUG > > +obj-$(CONFIG_MAX31827) += max31827.o > diff --git a/drivers/hwmon/max31827.c b/drivers/hwmon/max31827.c > new file mode 100644 > index 000000000000..1c79bcf12d78 > --- /dev/null > +++ b/drivers/hwmon/max31827.c > @@ -0,0 +1,240 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * max31827.c - Support for Maxim Low-Power Switch > + * > + * Copyright (c) 2023 Daniel Matyas <daniel.matyas@xxxxxxxxxx> > + */ > + > +#include <linux/bitfield.h> > +#include <linux/bits.h> > +#include <linux/device.h> > +#include <linux/of.h> > +#include <linux/i2c.h> > +#include <linux/module.h> > +#include <linux/regmap.h> > +#include <linux/hwmon.h> > +#include <linux/hwmon-sysfs.h> Not needed. > + > +#define MAX31827_T_REG 0x0 > +#define MAX31827_CONFIGURATION_REG 0x2 > +#define MAX31827_TH_REG 0x4 > +#define MAX31827_TL_REG 0x6 > +#define MAX31827_TH_HYST_REG 0x8 > +#define MAX31827_TL_HYST_REG 0xA > + > +#define MAX31827_CONFIGURATION_1SHOT_MASK BIT(0) > +#define MAX31827_CONFIGURATION_CNV_RATE_MASK GENMASK(3, 1) > +#define MAX31827_CONFIGURATION_RESOL_MASK GENMASK(7, 6) > +#define MAX31827_CONFIGURATION_U_TEMP_STAT_MASK BIT(14) > +#define MAX31827_CONFIGURATION_O_TEMP_STAT_MASK BIT(15) > + > +#define MAX31827_CNV_SHUTDOWN 0x0 > +#define MAX31827_CNV_1_DIV_64_HZ 0x1 > +#define MAX31827_CNV_1_DIV_32_HZ 0x2 > +#define MAX31827_CNV_1_DIV_16_HZ 0x3 > +#define MAX31827_CNV_1_DIV_4_HZ 0x4 > +#define MAX31827_CNV_1_HZ 0x5 > +#define MAX31827_CNV_4_HZ 0x6 > +#define MAX31827_CNV_8_HZ 0x7 > + Most of the above defines are not used. > +#define MAX31827_1SHOT_EN(x) ((x) ? BIT(0) : 0) x is either 0 or 1. This macro does not add any value. > + > +struct max31827_state { > + struct regmap *regmap; > + struct i2c_client *client; Not used anywhere. > +}; > + > +static const struct regmap_config max31827_regmap = { > + .reg_bits = 8, > + .val_bits = 16, > + .max_register = 0xA, > +}; > + > +static umode_t max31827_is_visible(const void *state, > + enum hwmon_sensor_types type, > + u32 attr, int channel) > +{ > + if (type == hwmon_temp) { > + switch (attr) { > + case hwmon_temp_enable: > + case hwmon_temp_max: > + case hwmon_temp_min: > + case hwmon_temp_max_hyst: > + case hwmon_temp_min_hyst: > + return 0644; > + case hwmon_temp_input: > + return 0444; > + } > + } > + > + return 0; > +} > + > +static int max31827_read(struct device *dev, enum hwmon_sensor_types type, > + u32 attr, int channel, long *val) > +{ > + struct max31827_state *st; > + unsigned int uval; > + int ret; > + > + st = dev_get_drvdata(dev); Please be consistent: Either assign in the declaration, or later, but don't mix the two. > + if (IS_ERR(st)) > + return PTR_ERR(st); Unnecessary check. > + > + if (type != hwmon_temp) > + return -EOPNOTSUPP; > + > + switch (attr) { > + case hwmon_temp_enable: > + ret = regmap_read(st->regmap, MAX31827_CONFIGURATION_REG, &uval); > + uval = FIELD_GET(MAX31827_CONFIGURATION_1SHOT_MASK, uval); This is an ABI abuse. hwmon_temp_enable is expected to enable / disable the sensor (here: set conversion rate to 0), not to set 1-shot mode or to trigger a single conversion. If your application mandates 1-shot mode, do it properly. Implement continuous mode by default, have the _enable attribute disable the sensor as per ABI, and, if disabled, trigger one-shot mode when reading the temperature and let it wait until a temperature measurement is available. I'd strongly suggest to skip that and use a conversion rate of 1 / 64 seconds instead to keep the code simple. You might also want to consider implementing the update_interval attribute to let the user configure the conversion rate. > + break; > + > + case hwmon_temp_input: > + ret = regmap_read(st->regmap, MAX31827_T_REG, &uval); > + break; > + > + case hwmon_temp_max: > + ret = regmap_read(st->regmap, MAX31827_TH_REG, &uval); > + break; > + > + case hwmon_temp_max_hyst: > + ret = regmap_read(st->regmap, MAX31827_TH_HYST_REG, &uval); > + break; > + case hwmon_temp_min: > + ret = regmap_read(st->regmap, MAX31827_TL_REG, &uval); > + break; > + > + case hwmon_temp_min_hyst: > + ret = regmap_read(st->regmap, MAX31827_TL_HYST_REG, &uval); > + break; > + Why no alarm attribute suppport ? > + default: > + ret = -EOPNOTSUPP; > + } > + > + if (ret) > + return ret; > + > + *val = uval; > + > + return 0; > +} > + > +static int max31827_write(struct device *dev, enum hwmon_sensor_types type, > + u32 attr, int channel, long val) > +{ > + struct max31827_state *st = dev_get_drvdata(dev); > + > + if (IS_ERR(st)) > + return PTR_ERR(st); Unnecessary check. > + > + switch (attr) { > + case hwmon_temp_enable: > + if (val >> 1) > + return -EOPNOTSUPP; > + > + return regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG, > + MAX31827_CONFIGURATION_1SHOT_MASK, > + MAX31827_1SHOT_EN(val)); > + > + case hwmon_temp_max: > + return regmap_write(st->regmap, MAX31827_TH_REG, val); > + > + case hwmon_temp_max_hyst: > + return regmap_write(st->regmap, MAX31827_TH_HYST_REG, val); Datasheet: " Before the register values are changed over I2C, the part has to be placed in Shutdown mode. Refer to the Configuration/ Status Register Conversion Rate field for details. Operation in automatic mode can resume after the register update. " Yes, I understand, the driver currently always operates in shutdown/1-shot mode, but as mentioned above that is unacceptable. > + > + case hwmon_temp_min: > + return regmap_write(st->regmap, MAX31827_TL_REG, val); > + > + case hwmon_temp_min_hyst: > + return regmap_write(st->regmap, MAX31827_TL_HYST_REG, val); > + } > + > + return -EOPNOTSUPP; > +} > + > +static int max31827_init_client(struct max31827_state *st) > +{ > + return regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG, > + MAX31827_CONFIGURATION_CNV_RATE_MASK | > + MAX31827_CONFIGURATION_1SHOT_MASK, > + MAX31827_1SHOT_EN(1)); More ABI abuse. This configures the driver (hard) for 1-shot mode, and assumes that a conversion is triggered by writing into the _enable attribute. Sorry, this is unacceptable. > +} > + > +static const struct hwmon_channel_info *max31827_info[] = { > + HWMON_CHANNEL_INFO(temp, HWMON_T_ENABLE | HWMON_T_INPUT | HWMON_T_MIN | > + HWMON_T_MIN_HYST | HWMON_T_MAX | HWMON_T_MAX_HYST), > + NULL, > +}; > + > +static const struct hwmon_ops max31827_hwmon_ops = { > + .is_visible = max31827_is_visible, > + .read = max31827_read, > + .write = max31827_write, > +}; > + > +static const struct hwmon_chip_info max31827_chip_info = { > + .ops = &max31827_hwmon_ops, > + .info = max31827_info, > +}; > + > +static int max31827_probe(struct i2c_client *client) > +{ > + struct device *dev = &client->dev; > + struct device *hwmon_dev; > + struct max31827_state *st; > + int ret; > + > + if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA)) > + return -EOPNOTSUPP; > + > + st = devm_kzalloc(dev, sizeof(struct max31827_state), GFP_KERNEL); > + if (!st) > + return -ENOMEM; > + > + st->client = client; > + > + st->regmap = devm_regmap_init_i2c(client, &max31827_regmap); > + if (IS_ERR(st->regmap)) > + return dev_err_probe(dev, PTR_ERR(st->regmap), > + "Failed to allocate regmap: %ld\n", > + PTR_ERR(st->regmap)); dev_err_probe() already displays an error text. > + > + ret = max31827_init_client(st); > + if (ret) > + return ret; > + > + hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, st, > + &max31827_chip_info, > + NULL); > + > + return PTR_ERR_OR_ZERO(hwmon_dev); > +} > + > +static const struct i2c_device_id max31827_i2c_ids[] = { > + { .name = "max31827" }, > + { } > +}; > +MODULE_DEVICE_TABLE(i2c, max31827_i2c_ids); > + > +static const struct of_device_id max31827_of_match[] = { > + { .compatible = "max31827" }, > + { } > +}; > +MODULE_DEVICE_TABLE(of, max31827_of_match); > + > +static struct i2c_driver max31827_driver = { > + .class = I2C_CLASS_HWMON, > + .driver = { > + .name = "max31827", > + .of_match_table = max31827_of_match, > + }, > + .probe_new = max31827_probe, > + .id_table = max31827_i2c_ids, > +}; > +module_i2c_driver(max31827_driver); > + > +MODULE_AUTHOR("Daniel Matyas <daniel.matyas@xxxxxxxxxx>"); > +MODULE_DESCRIPTION("Maxim MAX31827 low-power temperature switch driver"); > +MODULE_LICENSE("GPL"); > -- > 2.34.1 >
